Mcdonalds dissapoints again

Bought food from mcdonalds somerset west N2 Heritage park branch, and once again, and probably 6/10 times we did not receive our complete order. If it is not burgers missing, it is 2 jalapeno sauces as of tonight, or fries. There is no use to drive back from home and use R30 of fuel for R12 of sauce. But after numerous times its so annoying to be dissapointed in the inabillity of omployees to read a screen and deliver the order. This is not suppose to be difficult, so my question is why are you so perfect on making these mistakes. Is it purposefull theft of employees or are they just illiterate to read a computer screen? For the only car in the drive through and one client in the restaurant a person should not wait 15 minutes in the parking area for food, and then to receive the an incomplete order.